MarineAir Passport Unit not heating

[richk]

I have two Marine Air compressors on my boat; one fwd and one aft. Just started the fwd one today to see if I could dehumidify the boat. It wouldn't go into heat mode. The aft unit runs fine in heat mode. There's a single raw water intake and two discharges, one for each unit. Both discharges had steady flow.

Any ideas why I can't get the fwd unit into heat mode?

Baffled on the Chesapeake
Rich

 

[quadrille38]

This may be way to simple and obvious but the control is programmable such that you can have heat only, cool only or auto. Make sure it's not on cool only. There are instructions in the manual and I think you can get them on line telling you how to program. It's very simple.


One other suggestion is that there is a setting in programming that you use to set ambient temperature. It's sort of calibration for the thermostat. It's not terribly precise - something like + or - 5 or 10 degrees. I had to get a thermometer and use it to adjust my unit. If it's too far off the actual temperature it might not trigger heat when you want it.

 

[kloudie1]

Does the compressor run on cool mode and not on heat? Is the switchover valve working ?
Is the fan coming on? Switchover valve is a powered solenoid valve that changes the refrigerant flow from evap to condenser coils and vice versa.. If it sticks or fails, the unit will stay in the "cool" mode which would result in cooling instead of heating when it is run in the heat mode. If the compressor is not running, the unit would not heat or cool but th fan and water pumps might run. Compressor not running could be a loose connection a bad capacitor a faulty thermostat or a bad compressor..

 

[richk]

Thanks to both Kloudie1 and Quadrille38.
It occured to me that since the units are programmable and the batteries were disconnected for the winter then reconnected that the aft unit remembered the settings and the fwd one didn't. I'll try that suggestion first.
The second one means I need to locate the solenoid and give it a tap to see if its stuck.

Thanks again
Cool Rich in cool annapolis (both refer to temps not attitudes!)

 

[quadrille38]

Another suggestion as this just happened to friends whose new last year boat isn't heating this year.

They tried the reversing valve and even followed the instructions in the manual that say to gently tap on it with a rubber mallet to see if it's stuck. That didn't work.

What they discovered is that the refrigerant had leaked out so there is nothing for the compressor to compress. It was described as oil like feel under the compressor. Service man has been scheduled.